Refrigerating apparatus



Feb. '21, 1939. F. CONRAD 2,143,412

REFRIGERATING APPARATUS Filed Jan. 19, 1933 V mvENTok G :3 Fmmx Comma.

BY C515,.M

A'ITORNEY Patented Feb. 21, 1939 UNITED STATES PATENT OFFICE,

2,148,412 REFRIGERATING APPARATUS Frank Conrad, Pittsburgh, Pa.,assignor to Westinghouse Electric & Manufacturing Company,

East Pittsburgh, Pa., a. corporation of Pennsylvania Application January19, 1933, Serial No. 652,535

18 Claims.

My invention relates to refrigerating apparatus,

" statically-controlled expansion valves. These valves, however, areopen to the objection that they are complicated and expensive, andrequire a separate connection from the refrigerant line to eachevaporator.

I have found that capillary tubes are very satisfactory to distributerefrigerant to a plurality of evaporators connected in parallel, thecapillary tubes also acting as fixed resistance expansion valves. Wherethe" evaporators are not equally loaded, the capillary tubes efiectivelytend, as

compared with conduits or other connections having only negligibleresistance to flow, to prevent the least loaded evaporator from starvingthe others since the largest pressure diife'rence between an inlet ofthe capillary tubes and the evaporatorsoccurs at the least'loadedevaporator due to the low pressure of the refrigerant therein, As thepressure difference between the ends of a tube conveying a. liquidincreases, the flow through the tube increases only as the square rootof the increase in pressure difference, and,therefore, there 'is atendency to prevent starvingof the other evaporators.

A' regulating valve is disposed in the supply conduit adjacent to thecapillary tubes to modify the action of the capillary tubes by eithermanual or automatic means, thereby regulating the amount of refrigerantdelivered to the cooling unit. The aforesaid automatic and manual meansare also adapted to completely shut oil? the flow ofrefriger'ant undercertain conditions. I I

The capillary tubes, however, being of constant orifice, allow liquidrefrigerant to be iorced'to the low pressure evaporators from thehighpressurc condenserwhen the compressor stops pumpine'ajwith aresultantpressure rise in the evaporators, so that the compressor maypump liquid on starting with resultant overload thereon, which mayresult in breaking of the combodiment ofmy invention;

pressor valves. In addition to this, if the pressure in the condenserrises unduly, more refrigerant is forced to the evaporator than thecompressor can pump away with resultant overload of the compressor. Toprevent overloading from these and other causes, the aforementionedregulating valve is connected in the system in such a manner that itresponds to a temperature or pressure condition thereofto automaticallycontrol the flow of refrigerant to the evaporator by partially orcompletely stopping the flow substantlally independently of the manualor automatic temperature-regulating means.

It is an object of my invention, therefore, to provide a novel controlmeans for a. plurality of evaporators connected in parallel to a commonsupply line.

It is another object of my invention to prevent overloading of thecompressor of refrigerating apparatus.

It is a further object of my invention to provide ,a refrigeratingsystem having a plurality of evaporators connected in parallel with acommon supply line in which the temperatures of the evaporators arecontrolled without the use of complicated and expensive devices.

These and other objects are effected by my invention, as will beapparent from the following description and claims taken in accordancewith the accompanying drawing, forming a part of this application, inwhich:

Fig. 1 is a. diagrammatic view of a compression refrigerating systemcontainingone preferred em- Fig. 2 is-an enlarged diagrammatic view-ofthe distributing and overload valve shown in Fig. 1; and,

Fig. 3 is an enlarged view of a second embodiment of the distributingand overload valve shown in Fig. 1.

Referring specifically to the drawing for a detailed description of myinvention,v numeral- 1- designates an electric motor which drives acompressor 2 which, in turn, pumps refrigerant to a condenser 3." Asrefrigerant is condensed, it'flows through a conduit 4 to a receivingtank 5.- Refrigerant flows'irom the receiving tank 5 through 1 supplyconduit 6 to an'expansion device generallyv designated at I and then toa cooling. device 8.,

wherein the refrigerant absorbs heat and is drawnback to the compressor2 through a con-' duit 9; *A- fan II, also drivenby the motor I, forcesa draft of cooling air over the compressor 2 and condenser}. The motoris supplied with energy through conductors Ita and Ill), and a switch I0is provided for starting and stopping the operation of compressor 2.

The cooling device 8 is preferably of such dimensions that, as more orless refrigerant is supplied thereto, its eifective cooling area isincreased or decreased, and is arranged so that the full cooling areawill be presented when the maximum expected load is handled by thecooling device. The cooling effect of the cooling device 8, therefore,is not dependent on the temperature thereof but is dependent on thepounds of refrigerant pumped thereto and evaporated therein per unit oftime.

The cooling device 8 is comprised of a plurality of evaporators or coils12, each having a capillary tube 13 connected to the supply conduit 6,whereby the evaporators are connected in parallel to the supply conduit.Since these tubes have constant lengths and bore diameters, the amountof refrigerant pumped to each coil l2 and, there fore, the refrigeratingeffect, depends on the resistance of the capillary tubes l3, and thepressure-difference between the supply line 6 and the coils l2, whichpressure-difference may be varied in many ways. The capillary tubes I!also act as expansion valves to supply low-pressure refrigerant to thecooling coils i2.

In order to modify the expansion qualities of the capillary tubes l3, athrottle valve I4 is disposed between them and the supply line. It willbe noted from Fig.2 that the inlet ends of the capillary tubes areconnected to the fitting at the outlet side of the valve ll at pointswhich are spaced closely to each other and which are equally advancedwith respect to the flow of refrigerant. It will also be noted from thedrawing that the mixture of liquid and vaporous refrigerant dischargedfrom the valve I4 is sub-divided'before the liquid and vapor haveappreciable opportunity for separation. This arrangement provides foruniformity of the mixture of liquid and vaporous refrigerant received bythe several tubes. The valve includes an orifice IS, a" seat It and aneedle II which coacts with the seat l6 and opens and closes the orificeii. The valve is normally operated by a handle l8 attached by suitablelinkage H to the needle II as shown in Fig. 2 By varying the adjustmentof the valve ll, the

amount of refrigerant delivered to and distributed by the capillarytubes is changed, or the refrigerant is entirely out off, and theeflective area of the cooling device I is, therefore, also changed.

In order to operate the valve I4 automatically in response to undulyhigh-pressure in the cooling device I, which may occur therein due tostopping of the compressor and other causes, and thusly preventoverloading of the compressor, a safety device including a Sylphonbellows 2| is connected by a conduit 22 to the interior of the coolingdevice 8. The closed end of the bellows is connected to. the needle llso that, when the pressure in the cooling device I rises, the Bylphon 2|expands and forces the needle I! into the valve orifice ll, thus closingor partly closing the valve N and allowing the pump 2 to lower thepressure in the coils l2. Also, when the compressor 2 stops V operating,the high-pressure prevailing in the condenser 8 will force liquidrefrigerant into the cooling device 8 through the unrestricted passagesof the capillary tubes II. The pressure in' the cooling device Ithereupon rises, and the valve I is then closed. Liquid refrigerant inthe lowside of the system then vaporize as the temperature thereof risesduring the oif-cycle period of the machine; the compressor. therefore,upon starting pumps only gasand breaking of valves due to pumping liquidis prevented.

In a second embodiment of my invention, a second Sylphon bellows 23replaces the manual adjustment i8, the remainder of the apparatus beingthe same. The bellows is filled with a suitable expansible liquid suchas ethyl chloride and is connected by a conduit 24 to a bulb 25 which ispositioned in an enclosure 26 which is to be cooled. The closed end ofthe bellows 23 is connected through suitable linkage 21 to the needle I!so that, as the temperature in the enclosure 26 is lowered the bellows23 contracts and forces the needle I! into the orifice l5, thus closing,or partly closing, the valve l4 and thus decreasing or stopping flow ofrefrigerant delivered to the cooling device.

From the foregoing description, it will be apparent that I have provideda novel control means for a plurality of refrigerating evaporators whichare connected in parallel to a common supply conduit, without the use ofexpensive and complicated devices. It is obvious that the various coilsof the evaporator need not be disposed together, and that the bore andlength of the capillary tube,,for each coil may vary so that therefrigerating effect of each coil is varied. The capillary tubes providefor distribution and expansion of the compressed refrigerant into aplurality of evaporating coils, and the valve it provides for modifyingthe expansion action of the capillary tubes, either manually or inresponse to the temperature of an enclosure to be cooled. The valve Italso prevents overloading of the compressor on starting, or when runningdue to other causes which raise the temperature and pressure of theevaporator to a point where the compressor cannot handle the media to beexhausted therefrom without danger of breaking the compressor valves andotherwise straining the compressor.

While I have shown my invention in two forms, it will be obvious tothose skilled in the art that it is not so limited, but is susceptibleof various other changes and modifications without departing from thespirit thereof, and I desire, therefore, that only such limitationsshall be placed thereupon as-are imposed by the prior art or as arespecifically set forth in the appended claims.

What I claim is:

1. In a refrigerating system, a common rei'rigerant supply conduit, aplurality of evaporators, and a plurality of capillary tubes con nectingthe evaporators in parallel to said capillary tubes for distributing andexpanding refrigerant from said common supply conduit to each of saidevaporators, and a valve disposed between said supply conduit and saidcapillary tubes, means for adjusting the valve and means independent ofthe adjusting means responsive to a characteristic of pressure andtemperature of said system for operating the valve.

2. In a refrigerating system, a common reirigerant supply conduit, aplurality of evaporators, a plurality of capillary tubes connecting saidevaporators in parallel to said capillary tubes for distributing andexpanding refrigerant from said common supply conduit to each of saidevaporators, and a valve disposed between said supply conduit and saidcapillary tubes, means for adjusting the valve and means independent ofthe adjusting means responsive to the pressure of said evaporator tooperate the valve.

3. In a refrigerating system, a common refrigerant supply conduit, aplurality of evaporators, a plurality of capillary tubes connecting theevaporators in parallel to said refrigerant supply conduit fordistributing and expanding refrigerant to each of said evaporators, anda manually adjustable valve disposed between said supply conduit andsaid tubes to modify the action of said tubes, said valve also beingprovided with'means responsive to a characteristic of pressure andtemperature of said system for operating said adjustable valve.

4. In a refrigerating system in which a refrigerant is successivelycompressed, condensed and evaporated, an evaporator comprising aplurality of coils having separate inlets, an expansion device ofconstant length and orifice con.- nected to the inlet of each evaporatorcoil, an adjustable valve for controlling the flow of refrigerant tosaid expansion devices, and means for adjusting said valve'in responseto the pressure of the evaporator.

5. In a refrigerating system in which a refrigerant is successivelycompressed, condensed and evaporated, an evaporator comprising aplurality of coils having separate inlets, an expansion means ofconstant length and orifice connected to the inlet of each evaporatorcoil and an adjustable valve for controlling the flow of refrigerant tosaid expansion devices, said valve being adjustable both manually and inresponse to the pressure of the evaporator.

6. In a. refrigerating system in which a refrigerant is successivelycompressed, condensed and evaporated, an enclosure to be cooled by saidsystem, an evaporator in heat exchange relation with said enclosure,said evaporator comprising a plurality of coils having separate inlets,an expansion means of constant length and orifice connected to the inletof each evaporator coil,- and an adjustable valve responsive to thetemperature of said enclosure for controlling the flow of refrigerant tosaid expansion devices.

7. In a refrigerating system in which a refrigerant is successivelycompressed condensed and evaporated, an enclosure to be cooled by saidsystem, an evaporator in heat exchange relation with saidenclosure, saidevaporator comprising a plurality of coils having separate inlets, anexpansion means of constant length and orifice connected to the inlet ofeach evaporator coil, and an adjustable valve responsive to thetemperature of said enclosure for controlling the flow of refrigerant tosaid expansion devices, said valve being also manually adjustable.

8. In a refrigerating system in which a refrigerant is successivelycompressed, condensed and evaporated, an enclosure to be cooled by saidsystem, an evaporator inheat exchange relation with said enclosure, saidevaporator comprising a plurality of coils having separate inlets, anexpansion means of constant len th and orifice connected to the inlet ofeach evaporator coil, an adjustable valve responsive to the temperatureof said enclosure for controlling the flow of refrigerant to saidexpansion devices, and mean's'responsive to a pressure-temperaturecharacteristicof said system for also operating said valve.

9. In a refrigerating systemin which a refrigerant is successivelycompressed, condensed and evaporated, an evaporator comprising aplurality of coils having separate refrigerant inlets, a capillary tubeconnected to the inlet, of each evaporator 'coil forexpandingrefrigerant into the coil, 9. shut-off valve for stopping the flow cfrefrigerant through the capillary tubes to the coils, and meansresponsive to a pressure condition in the coils for operating theshut-off valve.

10. In. a refrigerating system comprising a condenser, a liquidreceiver, a plurality of evaporators of the'dry type, a compressor,means for driving the compressonand means for starting and stopping thecompressor driving means; the combination of a common refrigerant supplyconduit for delivering refrigerant to said evaporators from the liquidreceiver, a plurality of capillary tubes connecting the evaporators inparallel to said conduit for distributing and expanding refrigerant intoeach evaporator, and an automatically operable valve for shutting offthe flow of refrigerant from the supply conduit to the evaporators whenthe compressor is stopped.

11. In a refrigerating system comprising a condenser, a liquid receiver,a plurality of evaporators of the dry type, a compressor, means fordriving the compressor, and means for starting and stopping thecompressor driving means; the combination of a ,common refrigerantsupply conduit for delivering refrigerant to said evaporators from theliquid receiver, a plurality of capillary tubes connecting theevaporators in parallel to said conduit for distributing and expandingrefrigerant into each evaporator, and a valve for shutting off the flowof refrigerant from the supply conduit to the evaporators in response toa condition resulting from stopping of the compressor.

12. In refrigerating apparatus, the combination of a compressor, meansfor driving the compressor, means for starting and stopping thecompressor and its driving means, a condenser connected to the outlet ofthe compressor, a liquid receiver connected to the outlet of thecondenser, a plurality of evaporators of the dry type connected to theinlet of the compressor, conduit means for conveying refrigerant fromthe liquid receiver to the evaporators and inant to the evaporators, andmeans for shutting off fiow of refrigerant through said conveying meansin response to a condition in the apparatus substantially concurrentwith stopping of the compressor for preventing accumulation of liquidrefrigerant between the capillary tubes and the inlet of the compressorwhile the latter is stopped.

13. Refrigerating apparatus comprising the combination of a plurality ofevaporator elements of the dry type; a common liquid refrigerant supplyconduit therefor; and means for expanding liquid refrigerant suppliedfrom said conduit to said evaporator elements, for regulating saidexpansion and for distributing the same to the several evaporatorelements comprising an expansion v'alve anda group of restrictedflow-resistance passages, through which valve and group of passages therefrigerant flows in series and in each of which it is partiallyexpanded, and means responsive to anoperating condition of theevaporator elements for controlling said valve, whereby saidvalve andflowresistance'passages together effect expansion of the refrigerant,said valve regulates said .expansion, and saidilow-resistance passagesdistribute the refrigerant among the evaporator elements, said passageshaving their entrant ends closely spaced for proper division ofrefrigerant therebetween.

l4. Refrigerating apparatus comprising the combination of a plurality ofevaporator elements arranged to efiect a common cooling action, commonliquid refrigerant supply means therefor, and means for distributingrefrigerant from said supply means to said evaporator elements and foreffecting expansion and regulating the flow thereof, said last-mentionedmeans including a plurality of fixed restricted passages or orificesconnected respectively to the inlet ends of the several evaporatorelements for distributing refrigerant thereto, a valve connected betweensaid supply means and said restricted passages or orifices forregulating the flow of the refrigerant, and means operable automaticallyin response to pressure of the refrigerant in said evaporator elementsfor regulating said valve.

15. Refrigerating apparatus comprising the combination of a plurality ofevaporator elements of the dry type arranged to effect a common coolingaction, common liquid refrigerant supply means therefor, and means fordistributing refrigerant from said supply means to said evaporatorelements and for effecting expansion and regulating the flow thereof,said last-mentioned means including a plurality of fixed elongatedpassages of restricted flow area connected respectively to the inletends of the several evaporator elements for distributing refrigerantthereto, a valve connected between said simply means and said restrictedpassages for regulating the flow of the refrigerant, and means operableautomatically in response to an operating condition of the evaporatorelements for regulating said valve, said restricted passages havingtheir entrant ends closely spaced for proper distribution of refrigerantthereto.

16. Refrigerating apparatus comprising the combination of a plurality ofevaporator elements arranged to effect a common cooling action, commonliquid refrigerant supply means therefor, and means for distributingrefrigerant from said supply means to said evaporator elements and foreffecting expansion and regulat ing the flow thereof, saidlast-mentioned means including a plurality of tubes of restricted flowarea connected respectively to the inlet ends of the several evaporatorelements for distributing refrigerant thereto, a valve connected betweensaid supply means and said restricted tubes for regulating the flow oi'the refrigerant, and means operable automatically in response topressure of the refrigerant in said evaporator elements for regulatingsaid valve.

1'7. In refrigerating apparatus having a plurality of evaporatorelements, an expansion mechanism for said evaporator elements comprisingan expansion valve, means for operating said valve in response to anoperating condition of the refrigerating apparatus, a distributorfitting connected to the output side of said valve, said fitting havinga plurality -of orifice outlets grouped closely together and disposed atpoints which are equally advanced with respect to the flow of therefrigerant, said outlets communicating respectively with saidevaporator elements for distributing refrigerant thereto, the

expansion mechanism being constructed and arranged so that the mixtureof liquid and vaporous refrigerant is subdividedby the outlets beforethe liquid and vapor have appreciable opportunity for separation.

18. In refrigerating apparatus, the combination of a plurality ofevaporator elements arranged to effect a common cooling action, commonliquid refrigerant supply means therefor, and means for distributingrefrigerant from said supply means to said evaporator elements and foreffecting expansion and regulating the flow thereof, said last-mentionedmeans including an expansion valve, means for operating said valve inresponse to an operating condition of the refrigerating apparatus, adistributor head connected to the outlet side of said valve, a pluralityof tubes of restricted flow area extending from said dstributor head tosaid evaporator elements, the inlet ends of said tubes being connectedto said distributor head and arranged in a cluster and at points whichare equally advanced with respect to flow of the refrigerant, thedistributing and regulating means being constructed and arranged so thatthe mixture of liquid and vaporous refrigerant is subdivided by thetubes before the liquid and vapor have appreciable opportunity forseparation,

FRANK CONRAD.

